Inline measurement for quality control from macro to micro laser applications

Abstract

The essential basis for a reliable and target-aimed process control is the understanding of the interaction between the laser beam and the treated material and this was gained by thorough research on the influence of the process input parameters on the interaction sub processes and on the treatment result. The main players conducting this research over the decades have been research facilities and institutes and this research is still in progress. Since the moment when it was possible to achieve the necessary power density to start the process of deep penetration welding, accompanied by a keyhole, there is hope - and need - to measure e.g. the depth of this vapor channel. In the decades in which the technology of deep penetration welding has been used, various approaches have been developed that allow a message about the depth of the keyhole. The aim of this contribution is to show a compact overview on the different approaches to monitor and/or control micro and macro laser welding processes and especially bring out those which successfully have been transferred from laboratory to serial production in the recent past and will in the near future. Further use includes the acquisition of 3D images around the laser process itself, allowing for coaxial integration of pre- and post-process sensors.